This paper presents the design and fabrication of a compact 4-8GHz sweep frequency source at C-band with a hybrid frequency synthesizer technology. With DDS used as PLL’s reference, the frequency step size is as small as 3×10-4 Hz and the measured 1 kHz offset phase noise is-91.79dBc/Hz at 4GHz. This frequency sweep source has advantages of wide bandwidth, low phase noise, small frequency step size, low spurious, fast tuning speed, small size and low power consumption. So it is suitable for wireless hand-held test equipment and communication equipment.
The noise characteristics of multichannel systems of forming signals based on hybrid frequency synthesizers with automatic compensation of phase distortions of direct digital synthesizers, which are used in the composition of georadars with synthesized aperture, are investigated. It is established that the phase noise of the output signals of the formers at the 1 kHz detuning from the carrier oscillation at the output frequencies of the devices in the range from 500 to 3500 MHz is characterized by a level of minus 100 - minus 130 dB. In this case, the circuit of the signal former based on a hybrid frequency synthesizer with direct digital synthesizer as a reference oscillator of a phase locked loop is characterized by the worst noise characteristics but with the highest degree of autocompensation (about 13 dB). Conversely, the circuit of the signal former based on a hybrid frequency synthesizer with direct digital synthesizer as a support generator of the phase-locked loop has the best phase noises level from the considered variants of devices and least degree of autocompensation (about 6 dB).
A Low Phase-Noise Ka-Band Hybrid Frequency Synthesizer for Millimeter Wave Seeker
